My all time favorite rack is still the old Pletscher mousetrap, which I have on my Peugeot.

Whenever I use the Blackburn MTN rack on my Schwinn (mounted with adapter clamps on the seat stays, since the bike has no mudguard/rack lugs on the dropouts), I miss the mousetrap feature on the Pletscher.

Avoid the new Blackburns with two struts instead of the usual three. They are too flimsy to be of any use.

I feel the same way about the Pletscher above.

Yes, I've tried both of them.

+1

The Pletscher is a great rack if you aren't carrying much as they lack lateral stiffness and a proper touring rack will usually have triple stays to provide better support and add stiffness, especially if they are made of aluminium.

MEC in Canada offers a rather decent, triple stay rack that sells for $15.00... these will handle light to medium loads and for heavily loaded touring one would want something better.

Steel is a different animal... it does not suffer from the same fatigue issues that aluminium does and because of tubing dynamics a steel rack is not going to weigh much more and can often weigh less than a comparable aluminium rack because the tubes can be thinner and lighter for the same diameter. The Filzer rack that came off my Pugsley weighed 200 grams more than the rack I built and was flimsy in comparison.

One caveat is that a really nice steel rack will probably cost quite a bit more than an aluminium one... many are custom made and many of the mass produced ones tend to be of very poor quality which is true for many things.